How to use TypeScript native tuple support In Javascript
Tuple type is simpler to infer by adding native support for them in TypeScript. Developers can define tuple types explicitly and enjoy TypeScript’s type inference feature that will infer the type of the first element as a tuple. This approach provides strong typing and increases code maintainability.
Syntax:
// Define a tuple type
type MyTuple = [string, number, boolean];
// Infer the first element as a tuple
type FirstElementAsTuple = MyTuple extends [infer First, ...infer Rest] ? [First] : never;
Example: To infer the first element of type as tuple type using native tuple support.
// Define a tuple type
type MyTuple = [string, number, boolean];
// Infer the first element as a tuple
type FirstElementAsTuple =
MyTuple extends [infer First, ...infer Rest] ? [First] : never;
// Usage
const tuple: MyTuple = ['hello', 42, true];
// firstElement has type [string]
const firstElement: FirstElementAsTuple = [tuple[0]];
// Output
console.log("TypeScript Output:");
console.log("Tuple:", tuple);
console.log("First Element as Tuple:", firstElement);
Output:
Tuple: [ 'hello', 42, true ] First Element as Tuple: [ 'hello' ]
In the TypeScript approach, we leverage TypeScript’s type system to create a tuple type (MyTuple) and then employ conditional types to deduce the type of the first element as a tuple (FirstElementAsTuple).
How to Infer First Element of a Tuple as a Tuple Type ?
Tuples can be represented as arrays or objects in TypeScript. This will be achieved by knowing Typescript’s type system and methods such as manual inference as well as the use of the advanced type system of TypeScript.
Defining a tuple type in TypeScript resembles the array syntax with the possibility to specify the type for each element position.
Table of Content
- Using TypeScript native tuple support
- Conditional type using infer
- Mapped Types
- Manual Inference to Extract First Element as Tuple Type
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